Sensor arrangements and methods of production thereof

ABSTRACT

A sensor arrangement includes at least one sensor element with electrical connections and arranged in a solid plastic-material body, and at least a first electrically insulating layer which embeds the sensor element arranged between the sensor element and the plastic-material body, wherein the first electrically insulating layer includes a liquid polymer, and the plastic-material body is closed in an end region at least to such extent that the liquid polymer is sealed inside the plastic-material body in an airtight manner.

RELATED APPLICATIONS

This is a divisional of U.S. Ser. No. 13/255,323, filed Sep. 8, 2011, which is a §371 of International Application No. PCT/EP2010/053843, with an international filing date of Mar. 24, 2010 (WO 2010/108961, published Sep. 30, 2010), which is based on German Patent Application No. 10 2009 015 315.2, filed Mar. 27, 2009.

TECHNICAL FIELD

This disclosure relates to sensor arrangements and methods of producing such sensor arrangements.

BACKGROUND

DE 102008022465 A1 discloses a sensor arrangement which has a protective enclosure to protect a sensor element. It could nonetheless be helpful to provide a sensor arrangement that has sufficient electrical protection, while the response time of the sensor element is restricted only a little by the protection.

SUMMARY

We provide sensor arrangements including at least one sensor element with electrical connections and arranged in a solid plastic-material body, and at least a first electrically insulating layer which embeds the sensor element arranged between the sensor element and the plastic-material body, wherein the first electrically insulating layer includes a liquid polymer, and the plastic-material body is closed in an end region at least to such extent that the liquid polymer is sealed inside the plastic-material body in an airtight manner.

We also provide methods of producing sensor arrangements including providing a plastic-material body having a hollow space in which at least one sensor element is positioned, and arranging the at least a first electrically insulating layer in the hollow space between the sensor element and the plastic-material body such that the first electrically insulating layer embeds the sensor element, wherein the first electrically insulating layer includes a liquid polymer, and the plastic-material body is closed in an end region at least to such extent that the liquid polymer is sealed inside the plastic-material body in an airtight manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the schematic structure of a first example of a sensor arrangement.

FIG. 2 shows a further example of a sensor arrangement.

FIG. 3 shows a further example of a sensor arrangement which includes a sensor element and an optoelectronic component.

LIST OF REFERENCE SIGNS

-   1, 11 sensor element -   2, 2′ electrical connection -   3, 13 plastic-material body -   4, 14, 24 first insulating layer -   5 further insulating layer -   6 optoelectronic component -   7 hollow space in the plastic-material body 3 -   8 carrier -   12 conductor track

DETAILED DESCRIPTION

We provide a sensor arrangement which has at least one sensor element. The sensor element has electrical connections, by which the sensor element is electrically contacted. The sensor element is arranged in a solid plastic-material body. A solid plastic-material body should be understood as meaning a body made of a flexible plastic that has a defined basic form. The plastic-material body can be at least partially deformed, while the plastic-material body reverts again to its original form at any time. The electrical connections preferably extend beyond the dimensions of the plastic-material body.

Arranged between the sensor element and the plastic-material body is at least one insulating layer which embeds the sensor element. At least a partition of the electrical connections adjacent the sensor element is surrounded by the first insulating layer. The first insulating layer extends from the sensor element to the adjacent partitions of the electrical connections. Preferably, at least the region of the electrical connections is surrounded by the first insulating layer which is located in the interior space of the plastic-material body.

In one example, the sensor element directly senses at least one physical parameter of the medium to be measured. The sensor element is formed, for example, as a temperature sensor or as an optical sensor. In the case of a temperature sensor, for example, the temperature of the surrounding medium is sensed. In the case of an optical sensor, for example, optical signals acting on the sensor arrangement are sensed.

In one example of the sensor arrangement, a further insulating layer is arranged between the first insulating layer and the plastic-material body.

The plastic-material body preferably has a form which comprises at least one hollow space open to one side. However, the form of the plastic-material body is not restricted to such forms, but may have any form desired.

The material of the plastic-material body and the materials of the first insulating layer and the further insulating layers are preferably independent from one another. The materials are preferably made to meet their respective requirements and also have a high voltage endurance. In the case of a temperature sensor, the materials preferably have a high thermal conductivity. In the case of an optical sensor, the materials preferably have neutral optical properties with respect to the wavelength range sensed by the optical sensor. The materials are preferably as transparent as possible to the radiation in the wavelength range of the optical sensor.

The first insulating layer and the further insulating layer preferably comprise a flexible or solid polymer.

In an example of the sensor arrangement with a number of sensor elements, the individual sensor elements are respectively surrounded by the first insulating layer. In a further example, the sensor elements have a common first insulating layer, which surrounds all or some of the sensor elements.

In one example, the connections of the sensor element are configured as rigid supply leads. The supply leads preferably comprise a wire or a stranded conductor which remains in a certain alignment, the supply leads being configured such that they fix the sensor element at a specific position in the plastic-material body of the sensor arrangement.

In a further example, the sensor element has flexible supply leads or electrical connections.

In a yet further example, at least one sensor element is arranged on a rigid carrier or a printed circuit board, which is positioned in the plastic-material body.

In one example of the sensor arrangement, the plastic-material body has at least one guiding device suitable to position the sensor element at a defined location in the interior space of the plastic-material body. The guiding device is preferably arranged or formed such that between the sensor element and the guiding device of the plastic-material body, there is at least sufficient space for the first insulating layer surrounding the sensor element. The guiding device is formed, for example, as a web or projection.

At least one sensor element may have the function of a temperature sensor. Known temperature sensors are, for example, electrical components with NTC (Negative Temperature Coefficient) or PTC (Positive Temperature Coefficient) properties.

In a further example of the sensor arrangement, at least one sensor element has the function of an optical sensor.

At least one sensor element may be configured as a temperature sensor and a further sensor is formed as an optical sensor. Suitable, for example, as optical sensors are photodiodes or phototransistors.

In an example of the sensor arrangement with a temperature sensor and an optical sensor, it is possible for the temperature and optical signals to be sensed as simultaneously as possible.

In a further example, the sensor arrangement comprises an optoelectronic component. The optoelectronic component preferably has the properties of a light-emitting diode such as, for example, an LED or OLED.

In one example, the sensor arrangement comprises at least one optical sensor and at least one optoelectronic component arranged such that together they have, for example, the function of a light barrier.

In another example, the plastic-material body has a wall thickness of at least 1 mm at least in the region of the sensor element. The wall thickness of the plastic-material body in the region of the electrical supply leads of the sensor arrangement may be both less than and greater than the wall thickness in the region of the sensor element. Preferably, the plastic-material body has a wall thickness of at least 1 mm at least in the region in which the sensor arrangement is in contact with the medium to be measured.

In one example of the sensor arrangement, the sensor arrangement has a voltage endurance of at least 3000 V AC (alternating current). The voltage endurance of the sensor arrangement is a result of the sum of the voltage endurances of the individual insulating layers of the arrangement.

In another example of the sensor arrangement, the first insulating layer has a voltage endurance of preferably at least 1000 V AC. Particularly preferably, the first insulating layer has a voltage endurance of 1250 V AC.

The sensor arrangement has a voltage endurance of protection class II as specified by the VDE standard by being constructed such. The protection class is achieved at least in the region of the sensor element and in partitions of the electrical connections adjacent this region. The sensor arrangement is of protection class II at least in the region in which the sensor arrangement is in contact with the medium to be measured. Open electrical connections for the further electrical contacting of the sensor arrangement generally do not have voltage endurance to protection class II, but the protective arrangement may, for example, have a plug-in connection that conforms to protection class II. Consequently, for example, the complete sensor arrangement conforms to protection class II. A structure of the sensor arrangement as described above ensures that the response time of the sensor element is not restricted to any inadmissibly great extent by the insulation, and the sensor arrangement is suitable for rapid sensing of physical properties such as, for example, the temperature or an optical signal acting on the sensor arrangement.

In a method of producing a sensor arrangement as described above, a plastic-material body which has a hollow space is provided. At least one sensor element with electrical connections is positioned in the hollow space of the plastic-material body.

In one example, the sensor element is at a previously fixed distance from the plastic-material body so that the sensor element is arranged at a defined location of the hollow space.

In one example of the method, at least the hollow space in the region of the sensor element is filled with a polymer. The polymer preferably fills the complete space around the sensor element, preferably with no air being present any longer in this region. Partial discharges at interfaces or in hollow spaces are thus avoided.

In a further example, the hollow space of the plastic-material body is filled with a polymer before the positioning of the sensor element. The polymer forms the first insulating layer of the sensor element. The sensor element is subsequently immersed in the polymer-filled hollow space of the plastic-material body up to the desired position.

In a yet further example of the method, the sensor element is embedded in a first insulating layer before the positioning in the hollow space of the plastic-material body. Suitable for this, for example, is an injection-molding process to encapsulate the sensor element and at least adjacent regions of the electrical connections in a first insulating layer.

In one example of the method, the sensor element enclosed by a first insulating layer and positioned in the hollow space of the plastic-material body is enclosed by a further insulating layer. At least the intermediate space between the first insulating layer of the sensor element and the plastic-material body is preferably filled with a polymer.

The above-described subject-matter and methods are explained in more detail on the basis of the following figures and examples.

The following description reveals that the drawings are schematic and should not be seen as true to scale. Elements that are the same as one another or assume the same function have the same reference signs.

FIG. 1 schematically shows the structure of a first example of the sensor arrangement. The sensor arrangement has a plastic-material body 3. Arranged in the space inside the plastic-material body 3 is a sensor element 1, which as shown, has rigid electrical connections 2, 2′. The sensor element 1 and the partitions of the electrical connections 2, 2′ that are shown in FIG. 1 are surrounded by a first insulating layer 4. In FIG. 1, only the relevant partition of the complete sensor arrangement is shown. The ends of the electrical connections 2, 2′ can be contacted, preferably from the outside, for contacting of the sensor element 1. The first insulating layer 4 preferably comprises a solid, liquid or flexible polymer. In an example of the first insulating layer 4 that comprises a liquid polymer, the plastic-material body 3 is preferably closed in the end region at least to such extent that the polymer is sealed off, preferably in an airtight manner, in the space inside the plastic-material body 3.

In FIG. 2, a schematic structure of a further example of the sensor arrangement is shown. The sensor arrangement comprises a plastic-material body 3 in the hollow space 7 of which a sensor element 1 is arranged. The sensor element 1 has electrical connections 2, 2′, the sensor element 1 and the electrical connections 2, 2′ being surrounded by a first insulating layer 14, at least in the shown partition of the sensor arrangement. There is an intermediate space between the first insulating layer 14 and the inner wall of the plastic-material body 3 which may form a further insulating layer 5. The further insulating layer 5 may, for example, comprise air or a polymer.

In an example in which the sensor element 1 of the sensor arrangement has the properties of a temperature sensor, the further insulating layer 5 is preferably a polymer which has a good thermal conductivity. In the case of an example in which the sensor element 1 has the properties of an optical sensor, the further insulating layer 5 is preferably an optically transparent gas or polymer.

FIG. 2 shows only the region of the plastic-material body 3 in which the sensor element 1 is arranged. The further region preferably has connections 2, 2′ that can be electrically contacted at least from the outside.

FIG. 3 schematically shows the structure of a further example of the sensor arrangement that has two components. At least one component is configured as a sensor element 11. A further component is configured as an optoelectronic component 6. The sensor arrangement comprises a plastic-material body 13 in the interior space of which a carrier 8 is arranged. The sensor element 11 and the optoelectronic component 6 are arranged on the carrier 8 with conductor tracks 12, 12′. The sensor element 11 and the optoelectronic component 6 are electrically contacted by conductor tracks 12, 12′. The interior space of the plastic-material body 13 is filled with a polymer which forms a first insulating layer 24 around the sensor element 11 and around the optoelectronic component 6. The plastic-material body encloses the carrier 8 in FIG. 3 preferably at least to such extent that the first insulating layer 24 which, for example, comprises a liquid or solid polymer, remains in the space inside the plastic-material body 13.

In the shown example, the sensor arrangement comprises an optical sensor such as, for example, a photodiode or a phototransistor. The optoelectronic component 6 is, for example, an LED. The sensor arrangement has, for example, the function of a light barrier.

Although it has only been possible in the examples to describe a limited number of possible developments, this disclosure is not so restricted. It is in principle possible for the sensor arrangement to comprise a number of sensor elements of different types or of the same type and to include further components, wherein the sensor arrangement is of protection class II.

The description of the specified items and the method is not restricted to the individual specific examples. Rather, to the extent that is technically feasible, the features of the individual examples may be combined with one another as desired. 

1. A sensor arrangement comprising: at least one sensor element with electrical connections and arranged in a solid plastic-material body, and at least a first electrically insulating layer which embeds the sensor element arranged between the sensor element and the plastic-material body, wherein the first electrically insulating layer comprises a liquid polymer, and the plastic-material body is closed in an end region at least to such extent that the liquid polymer is sealed inside the plastic-material body in an airtight manner.
 2. The sensor arrangement according to claim 1, wherein a further insulating layer is arranged between the first insulating layer and the plastic-material body.
 3. The sensor arrangement according to claim 1, wherein the further insulating layer comprises a polymer.
 4. The sensor arrangement according to claim 1, wherein the electrical connections are rigid supply leads.
 5. The sensor arrangement according to claim 1, wherein the at least one sensor element functions as a temperature sensor.
 6. The sensor arrangement according to claim 1, wherein the at least one sensor element functions as an optical sensor.
 7. The sensor arrangement according to claim 6, further comprising at least one optoelectronic component.
 8. The sensor arrangement according to claim 1, having an AC voltage endurance of at least 3000 V.
 9. The sensor arrangement according to claim 1, wherein the plastic-material body has a material thickness of at least 1 mm.
 10. A method of producing a sensor arrangement comprising: providing a plastic-material body having hollow space in which at least one sensor element is positioned, and arranging at least a first electrically insulating layer in the hollow space between the sensor element and the plastic-material body such that the first electrically insulating layer embeds the sensor element, wherein the first electrically insulating layer comprises a liquid polymer, and the plastic-material body is closed in an end region at least to such extent that the liquid polymer is sealed inside the plastic-material body in an airtight manner. 